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[Display omitted] • A total of 20 different paper sludges were investigated. • A wide range of biomethane potentials was determined. • Inhibiting substances for some paper sludge were identified. • Co-digestion resulted in methane yield increase of 5–10%. • The possibility of anaerobic co-digestion could be demonstrated. In this work, the feasibility of the anaerobic digestion of paper sludge as a co-substrate in anaerobic digestion mechanical–biological treatment (MBT) plants is investigated. In the first phase, the biochemical properties, biomethane potential (BMP), and pollutant contents of 20 different industrial paper sludges are determined. Following the general evaluation in the BMP tests, the second phase of the project involves the semi-continuous co-digestion of six paper sludges in continuous stirred reactors (CSTR). Paper sludges are categorized according to their origin within the pulp and paper mills: Deinking Sludge (DS), Primary Sludge (PS) and Biological Sludge (BS). The analysis of potentially inhibiting elements shows that the concentrations of chlororganic compounds, mineral oil and some heavy metals are highest in DS, while the mean heavy metal loads in all paper sludges are relatively low compared to other industrial sludges. Large differences in total solids (TS) and volatile solids (VS) contents are observed among the different paper sludges investigated, with DS having the highest TS due to the high inorganic contents. The BMP of the investigated sludges ranges from 90 to 355 NL CH 4 kg−1 VS. In subsequent semi-continuous co-digestion experiments simulating MBT conditions, three DS and two fiber sludges (a mixture of PS and BS) show good methane generation rates, while one fiber sludge causes inhibition and indicates an increase in viscosity. In general, co-digestion of paper sludge in anaerobic digestion MBT plants can be a viable option for energy production and also facilitates a safe disposal of the paper sludge digestates. [ABSTRACT FROM AUTHOR]

The present study investigates the effect on methane production from waste paper when co-digested with macroalgal biomass. Both feedstocks were previously mechanically pretreated to reduce their particle size. The study was planned according two factors: the feedstock to inoculum (F/I) ratio and the waste paper to macroalgae (WP/MA) ratio. The F/I ratios checked were 0.2, 0.3 and 0.4 and the WP/MA ratios were 0:100, 25:75, 50:50, 75:25 and 100:0. The highest methane yield (386 L kg −1 VS added ) was achieved at an F/I ratio of 0.2 and a WP/MA ratio of 50:50. A biodegradability index of 0.87 obtained in this study indicates complete conversion of feedstock at an optimum C/N ratio of 26. Synergistic effect was found for WP/MA 25:75, 50:50 and 75:25 mixing ratios compared with the substrates mono-digestion. [ABSTRACT FROM AUTHOR]

In the anaerobic digestion of lignocellulosic materials such as waste paper, the accessibility of microorganisms to the fermentable sugars is restricted by their complex structure. A mechanical pretreatment with a Hollander beater was assessed in order to reduce the biomass particle size and to increase the feedstock’ specific surface area available to the microorganisms, and therefore improve the biogas yield. Pretreatment of paper waste for 60 min improves the methane yield by 21%, from a value of 210 ml/gVS corresponding to untreated paper waste to 254 ml/gVS. 30 min pretreatment have no significant effect on the methane yield. A response surface methodology was used to evaluate the effect of the beating time and feedstock/inoculum ratio on the methane yield. An optimum methane yield of 253 ml/gVS was achieved at 55 min of beating pretreatment and a F/I ratio of 0.3. [ABSTRACT FROM AUTHOR]

Climate change and energy crises are twin challenges that require collective wisdom and polygeneration energy systems for sustainable development. Hydrogen is an abundant element in the universe that can shape the future of energy transmission and storage from electrons to molecules. This paper presents utilization of a solar PV assisted hydrogen and electricity production and storage system for a university transportation fleet of 43 student transit buses to reduce annual 9842 liter fuel consumption and 26.52 Mt CO 2 emissions. The system is designed, modeled, and simulated using TRNSYS® energy simulation software and optimized in TrnOpt linked to GenOpt for dynamic weather conditions of Gujrat (Pakistan), Fargo (USA), London (UK). As a model, the results of a 27kW p PV system are presented that assists an alkaline electrolyzer generating 12696 m3 hydrogen, 6348 m3 oxygen, 16848 KWh electricity exported to national grid and 11.56 GJ thermal energy annually. The proposed system generates energy vectors including hydrogen, electricity, heat, and oxygen with optimal performance during intermittent weathers. In this paper, a business model canvas is developed for solar PV assisted hydrogen production and storage system. These outputs can be accredited to the hydrogen as an energy alternative for green and sustainable future for transportation sector. [Display omitted] • A paradigm energy shift from electron to molecules for a sustainable future. • A Solar assisted polygeneration system is dynamically simulated and optimized in TRNSYS for various climate conditions. • Proposed 27kWp system effectively produces 12696 m³ hydrogen, 6348 m³ oxygen, and exports 16848 kWh electricity to grid. • The system cuts annual fuel consumption by 9842 liters for university fleet, reducing CO 2 emissions by 26.52 Mt annually. • Developed a business model for the sustainable application of solar PV-assisted hydrogen production in transportation. [ABSTRACT FROM AUTHOR]

The paper is devoted to the development of a device for protecting facilities with turn-to-turn insulation, namely transformers and wind generators in order to increase the reliability of operation of electrical power systems, renewable energy installations and energy storage systems. The paper presents the results of experimental studies of the parameters of a prototype frequency-dependent device, as well as an assessment of the effectiveness of suppression of high-frequency surge voltages by the proposed device. The results of four groups of measurements are shown, which were compared with each other and with the results of previously showed computer simulations. The high efficiency of the proposed device when influencing the slope and amplitude of short high-frequency transients is shown. It is indicated that the parameters proposed earlier in the simulation allow the device to be used effectively. A brief analysis of alternative methods and means of protection is provided, and the prospects for using the device as protective equipment for wind power plants are also considered. [ABSTRACT FROM AUTHOR]

Green hydrogen is crucial for society's access to peaceful, secure, and stable energy sources to flourish sustainably and get universal government support. To protect the environment and provide energy security, it is essential to use hydrogen as a sustainable fuel and energy source to cover the energy baseload. This paper investigates the developments of renewable energy (RE) and the potential for green hydrogen in the Middle East and North Africa (MENA) region. There is a considerable chance to use RE because of the MENA region's excellent solar radiation. On the other hand, many countries in the MENA region are classified as one of the poorest in water resources and are known to have water-energy challenges. This paper focuses on the water needed to produce hydrogen in countries with water scarcity. A strengths, weaknesses, opportunities, and threats (SWOT) analysis was performed for green hydrogen generation in the MENA, where recommendations for countries with a water-energy nexus can be made. Additionally, this paper offers suggestions for creating a sustainable hydrogen economy, such as cutting back on the domestic use of fossil fuels, subsidizing the renewable production industry, and supporting hydrogen manufacturing. • Green hydrogen production is highly affected by water scarcity. • SWOT analysis was performed on green hydrogen generation in the MENA. • Recommendations were provided on a country-by-country basis. [ABSTRACT FROM AUTHOR]

Pulp and paper industry is a water-intensive industry. This industry commonly produces considerable amount of effluent, especially from virgin raw materials processing. The effluent, namely pulp and paper mill effluent has the potential to adversely affect the receiving watercourses. However, the nutrients in the pulp and paper mill effluent could be reused as a substrate in biohydrogen production. In this study, photofermentative biohydrogen production was investigated using Rhodobacter sphaeroides and pulp and paper mill effluent as a substrate. An application of low power ultrasound on R. sphaeroides was predicted to increase photofermentative biohydrogen production but excessive ultrasound effects might inhibit the production due to possible cell disruption. Hence, various ultrasonication duration (5, 10 and 15 min) and amplitude (15%, 30% and 45%) were applied on the bacteria to determine the recommended ultrasonication conditions for improving biohydrogen production. The recommended conditions were operated at ultrasonication amplitude and duration of 30% and 10 min, respectively. A maximum biohydrogen yield of 9.62 mL bioH 2 /mL medium was obtained under this condition, which was 66.7% higher than the result obtained using R. sphaeroides without undergoing ultrasonication (control). The light efficiency and cell concentration were increased by 67% and 150%, respectively, using ultrasonication amplitude and duration of 30% and 10 min, respectively as compared to the control. The present results demonstrated that moderate power of ultrasonication applied on R. sphaeroides was an effective method for enhancing photofermentative biohydrogen production using raw pulp and paper mill effluent as a bioresource. [ABSTRACT FROM AUTHOR]

Pulp and paper industry is one of the most polluting, energy and water intensive industries in the world. Produced pulp and paper mill sludge (PPMS) faces a major problem for handling and its management. An anaerobic digestion has become an alternative source. This review provides a detailed summary of anaerobic digestion of PPMS – An overview of the developments and improvement opportunities. This paper explores the different pretreatment methods to enhance biogas production from the PPMS. First, the paper gives an overview of PPMS production, and then it reviews PPMS as a substrate for anaerobic digestion with or without pretreatment. Finally, it discuss the optimal condition and concentration of organic and inorganic compounds required for the anaerobic metabolic activity. Future research should focus on the combination of different pretreatment technologies, relationship between sludge composition, reactor design and its operation, and microbial community dynamics. [ABSTRACT FROM AUTHOR]

Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity. • Bioenergy retrofits can widen the product portfolio of the pulp and paper industry. • Bioenergy retrofits in Europe were comprehensively reviewed for the first time. • Drivers and barriers for the market uptake were assessed from different perspectives. • Retrofits support the REDII targets for advanced biofuels in transport sector. • Utilization of residues for bioenergy products improves mills' resource efficiency. [ABSTRACT FROM AUTHOR]

This work reports an innovative simulation method for effectively utilizing paper-mill sludge based on the co-gasification approach for energy-enriched renewable fuel production. An Aspen plus-based co-gasification model was developed to simulate and examine the synergetic effects of biomass and paper-mill sludge co-gasification. Initially, the model was validated using experimental data from the reported literature and found good agreement regarding gasification and co-gasification approaches. Sensitivity analysis of biomass gasification revealed that the maximum H 2 content of 29.6% and CO (36.0%), LHV (7.8 MJ/Nm3), 72.2% (CCE) was obtained at optimal (850 °C: temperature; 1 bar: pressure; 0.2: ER) conditions. Further, the H 2 proportion enhanced, and CO declined to 38.8 and 30.7% at the same operating conditions, respectively, with a co-gasification ratio of 50% compared to 0% (H 2 : 29.6% and CO: 36.0%). However, with increasing the co-gasification ratio beyond 20%, the CO content started to follow upward trends; at the same CGR, the H 2 , LHV, and CCE observed were 36.0%, 7.76 MJ/Nm3, and 65.2%, respectively. Hence, the developed co-gasification model can provide vital information for large-scale gasifier design, operating decisions, and optimization using different biomass blends. • Biomass and PMS utilization to produce renewable fuel. • Co-gasification parametric effects evaluation on product yield. • Increasing the proportion of PMS in feedstock mixture increases H 2 content. • 20% PMS co-gasification provided consistency with reported literature. [ABSTRACT FROM AUTHOR]

The production of green hydrogen through electrolysis, utilizing renewable energies, is recognized as a pivotal element in the pursuit of decarbonization. In order to attain cost competitiveness for green hydrogen, reasonable generation costs are imperative. To identify cost-effective import partners for Germany, given its limited green hydrogen production capabilities, this study undertakes an exhaustive techno-economic analysis to determine the potential Levelized Cost of Hydrogen in Germany, Norway, Spain, Algeria, Morocco, and Egypt for the year 2050, which represents a critical milestone in European decarbonization efforts. Employing a stochastic approach with Monte Carlo simulations, the paper marks a significant contribution for projecting future cost ranges, acknowledging the multitude of uncertainties inherent in related cost parameters and emphasizing the importance of randomness in these assessments. Country-specific Weighted Average Cost of Capital are calculated in order to create a refined understanding of political and economic influences on cost formation, rather than using a uniform value across all investigated nations. Key findings reveal that among the evaluated nations, PV-based hydrogen emerges as the most cost-efficient alternative in all countries except Norway, with Spain presenting the lowest Levelized Cost of Hydrogen at 1.66 €/kg to 3.12 €/kg, followed by Algeria (1.72 €/kg to 3.23 €/kg) and Morocco (1.73 €/kg to 3.28 €/kg). Consequently, for economically favorable import options, Germany is advised to prioritize PV-based hydrogen imports from these countries. Additionally, hydrogen derived from onshore wind in Norway (2.24 €/kg to 3.73 €/kg) offers a feasible import alternative. To ensure supply chain diversity and reduce dependency on a single source, a mixed import strategy is advisable. Despite having the lowest electricity cost, Egypt shows the highest Levelized Cost of Hydrogen, primarily due to a significant Weighted Average Cost of Capital. • LCOH projections for 2050 were determined through Monte Carlo Simulation. • PV-based hydrogen is the most cost-effective option in all countries except Norway. • Spain exhibits the lowest LCOH, followed by Algeria and Morocco. • Country-specific WACC variations significantly impact the LCOH. • Importing from Spain, Algeria, Morocco (PV), and Norway (onshore) is advised. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen carriers (LOHC) can be used as a lossless form of hydrogen storage at ambient conditions. The storage cycle consists of the exothermic hydrogenation of a hydrogen-lean molecule at the start of the transport, usually the hydrogen production site, becoming a hydrogen-rich molecule. This loaded molecule can be transported long distances or be used as long-term storage due to its ability to not lose hydrogen over long periods of time. At the site or time of required hydrogen production, the hydrogen can be released through an endothermic dehydrogenation reaction. LOHCs show similar properties to crude oils, such as petroleum and diesel, allowing easy handling and possibilities of integration with current infrastructure. Using this background, this paper reviews a variety of aspects of the LOHC life cycle, with a focus on currently studied materials. Important factors such as the hydrogenation and dehydrogenation requirements for each material are analysed to determine their ability to be used in current scenarios. Toluene and dibenzyltoluene are attractive options with promising storage attributes, however their dehydrogenation enthalpies remain a problem. The economic feasibility of LOHCs being used as a delivery device were briefly analysed. LOHCs have been shown to be the cheapest option for long distance transport (>200 km), and are cheaper than most at shorter distances in terms of specifically transport costs. The major capital cost of an LOHC delivery chain remains the initial investment for the raw materials and the cost of equipment for performing hydrogenation and dehydrogenation. Finally, some studies in developing the LOHC field were discussed, such as microwave enhancing parts of the process and mixing LOHCs to acquire more advantageous properties. • Efficient hydrogen storage solution for sustainable energy transportation and storage. • Enables safe and cost-effective hydrogen transportation and distribution networks. • Promotes renewable energy integration through versatile and scalable storage capabilities. • Facilitates decarbonization efforts by enabling long-term, stable hydrogen supply chains. [ABSTRACT FROM AUTHOR]

A range of existing and newly developed hydrogen standards, certification and labelling (SCL) schemes aim to promote the role of 'renewable', 'clean' or 'green' hydrogen in decarbonising energy transitions. This paper analyses a sample of these SCLs to assess their role in the scaling up of renewable hydrogen and its derivatives. To analyse these hydrogen SCLs, we embellish a novel conceptual framework that brings together Sustainability, Systems Thinking, and Governance (SSG) literatures. The results reveal noteworthy scheme differences in motivation, approach, criteria, and governance; highlighting the complex, interconnected, and dynamic reality within which energy systems are embedded. We consider whether the sustainable utilisation of renewable hydrogen is well-served by the proliferation of SCLs and recommend an SSG-informed approach. An SSG approach will better promote collaboration towards an authoritative, global, multistakeholder, compromise on hydrogen certification that balances economic considerations with social, and environmental dimensions. [Display omitted] • There is a proliferation of hydrogen standards, certification and labelling (SCL) schemes. • We analyse a sample of SCLs to investigate their role in scaling green hydrogen. • We employ a Sustainability, Systems Thinking, and Governance (SSG) approach. • We recommend an SSG lens to help craft a global multistakeholder initiative. [ABSTRACT FROM AUTHOR]

This paper investigates an innovative study on the performance of a hybrid condensing boiler-fuel cell micro-cogeneration system for single residential applications. It combines experimental and dynamic numerical investigations including renewable energy for green hydrogen production and solid storage. Basing on the hourly measurements for a typical winter day, a dynamic model was developed and validated against different home heating need. Highlighting the influence home energy needs on fuel cell operating mode, it shows that single homes with low energy demand led to reduce the fuel cell's yearly operation below 50 %. In low-energy homes, a reduction in fuel cell size led to an increase in yearly operation to 60-70 % and achieved a 55 % electrical coverage rate. The integration of metal hydride hydrogen solid storage, powered by renewable sources, is emphasized. This setup increases heat demand, influencing fuel cell operation. In winter season, fuel cell operated for an average of 611 h, compared to 61 h in summer. System efficiency averaged 91 % annually, peaked at 95 % in summer, and sustained 93 % when both FC and condensing boiler were switched on. [Display omitted] • Modeling of a hybrid Boiler-Fuel Cell MCHP system for residential energy management. • Calibration of the FC-MCHP model using experimental data from a real MCHP unit. • Electrical and thermal coverage of the FC-MCHP unit with green hydrogen production and storage under different scenarios. • Strategies for optimal hydrogen consumption in in residential application. • Impact of solid-state hydrogen storage on FC-MCHP consumption and thermal management. [ABSTRACT FROM AUTHOR]

This paper focuses on the design and use of a control system for a renewable energy production plant based on hydrogen. The proposed control system aims at ensuring the stability and smooth functionality of the plant, which consists of a (i) photovoltaic system connected to an electrolyzer through a battery, (ii) a DC/DC step down transformer, and (iii) an electrolyzer heat exchange system. In this study, solar irradiance is the main system input, and hydrogen production the main output. Since the system utilizes solar energy as input, it depends on the random input of solar irradiance, ambient temperature, and wind flow. Furthermore, the electrolyzer's functionality is subject to several operational variables including cell voltage, current, temperature, and pressure. The electrolyzer heat exchange system operates at specified water temperatures and flow rates. The DC/DC output voltage, and therefore the voltage supplied to the electrolyzer, is regulated by changing its duty cycle. To regulate hydrogen production in the renewable energy production plant, an efficient control system is required. Accordingly, in this work, a control system is designed accounting for three different electrolyzer technologies, alkaline, PEM (proton exchange membrane), and E-TAC (electrochemical - thermally activated chemical water splitting). Subsequently, the effectiveness of the control system is analyzed using Matlab and Simulink models. The main results indicate that the battery is a crucial element in the whole system as it supplies the necessary energy to the electrolyzer. By regulating the appropriate components, the proposed control system proved capable of minimizing power fluctuations and increasing system efficiency up to 20% depending on ambient conditions. Additionally, the results indicate E-TAC and PEM efficiencies 13% and 7% higher than alkaline, respectively. [Display omitted] • Design of a control system for three different electrolyzer technologies. • Use of control systems for electrolyzer voltage and heat exchange. • Photovoltaic system connected to an electrolytic one through a battery. • Proposed control system increases system efficiency up to 20%. [ABSTRACT FROM AUTHOR]

The development of sustainable energy sources has become a major challenge for society. Green hydrogen, produced through the electrolysis of water using renewable energy sources, offers a potential solution to reducing our dependence on fossil fuels. The paper examines the integration of green hydrogen into various sectors, such as transportation, industry, power generation, and heating, highlighting its potential to decarbonize traditionally carbon-intensive areas. Furthermore, it analyses the strategies and policies employed by the European Union, Australia, Japan, the United States, and Canada to drive the development and adoption of green hydrogen technologies. The challenges and barriers that need to be addressed to fully realize the potential of green hydrogen, such as technological limitations, infrastructure development, costs and economic feasibility, regulatory and policy frameworks, and public perception and acceptance, have been investigated. Recommendations for overcoming these challenges and accelerating the adoption of green hydrogen technologies are provided, and the importance of research and development in this sector is emphasized. • Green hydrogen offers a sustainable solution to reduce fossil fuel dependency, decarbonizing key sectors. • Analyzed policies from the EU, Australia, Japan, the US, and Canada to foster green hydrogen technologies. • Discussing challenges: green hydrogen potential, tech limits, infrastructure, costs, regs, and public views. • Emphasized the importance of R&D and offers accelerating the adoption of green hydrogen technologies. [ABSTRACT FROM AUTHOR]

In this paper, a novel stochastic risk-averse mixed-integer linear programming (MILP) model is developed for optimal electricity procurement of hydrogen fuel stations (HFSs) with responsive hydrogen demands. In the developed model, HFS operator may procure its required electricity through day-ahead (DA) market, bilateral contracts, a contract with withdrawal penalty (CWP) and balancing market. The HFS is committed to inject a pre-specified volume of hydrogen into a natural gas network. In the developed stochastic model, the uncertainties in hydrogen demand and DA market prices are characterized as random variables and modeled as scenarios. The developed model is a two-stage model in which the decisions on transactions with bilateral contracts are the first-stage decision variables and the other decision variables belong to the second stage. The risk of suffering from high procurement costs is modeled using the Conditional Value at Risk (CVaR). The results confirm the efficiency of the proposed model both in terms of reduction in HFS expected cost and risk alleviation. The results show that the transaction through bilateral contracts decreases the expected cost and CVaR respectively by 6% and 3%. The results also indicate that the participation in the balancing market decreases the expected cost and CVaR respectively by 6% and 1.6%. As per results, in scenarios in which DA market prices are lower than CWP prices, HFS operator prefers to pay a penalty fee and withdraw from CWP. The sensitivity of HFS profit to the weight factor of risk metric and the participation factor of responsive demands are assessed. [Display omitted] • A model is developed for electricity procurement of hydrogen fuel stations (HFSs). • The uncertainties in demands and market prices are considered. • HFS procures electricity by day-ahead and balancing market and bilateral contracts. • Impact of different markets and transactions on HFS profit is assessed. • Sensitivity of HFS profit to weight of risk metric is assessed. [ABSTRACT FROM AUTHOR]

Renewable energies are available as clean sources to replace fossil fuels. Providing continuous power without compromising the environment through hybridizing solar and biomass source is one of the promising solutions. This paper seeks to address thermodynamic, economic, and environmental analysis of a multi-generation system with the aim of supplying heating, cooling, electricity, fresh-water, and hydrogen. To do this, the considered system is divided into on-peak, mid-peak, and off-peak periods and modeled based on the consumption pattern at different hours of the day and night. Due to the availability of renewable energy during peak consumption periods, biomass, solar, and hybrid biomass-solar energies are used as energy sources. This leads to a reduction in biomass consumption and carbon dioxide emissions through storing approximately 10 tons of biomass during the day. A sensitivity analysis of the factors affecting the system's function indicated that a growth in solar radiation from 600 to 1000 W/m2, results in a 35% improvement in exergy efficiency, a 2.7% raise in the total cost rate, and a 32.4% drop in CO 2 emissions of the system. Moreover, by changing the biomass flow rate from 0.5 to 1.5 kg/s, the exergy efficiency and total cost rate improved by 9.28%, 1.3%, respectively, and the CO 2 emissions rate increased from 0.41 to 1.14 tons/MWh. In addition, focusing on addressing economic and environmental concerns, the optimization of the proposed hybrid system is performed in two categories of objective functions. In the second category optimization, exergy efficiency, fresh water production, total cost rate and CO 2 emissions are determined as 31.75%, 74.75 kg/s, 324.60 $/h and 3.55 tons/MWh, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the impacts of economic (in)stability on carbon emissions and the role of renewable energy in these effects at the crossroads of accelerated climate change and rising global economic instability. The paper hypothesizes that these implications should be examined not by direct impacts across variables, but rather via indirect effects serially mediated by renewable energy consumption and economic growth. This paper analyzes the United States from January 1980 and April 2022 using manifest structural equation modeling. The paper reaches two major conclusions. First, there are clear distinctions between (i) the direct and indirect effects of economic stability, surrogated by inflation and policy interest rate, on carbon emissions, (ii) the symmetric and asymmetric indirect effects, and (iii) the roles of aggregate renewable energy and its components, such as biomass and hydropower energy use, in mediating these symmetric and asymmetric indirect effects. Second, renewable energy significantly reduces the carbon-increasing effects of inflation and interest rates. The paper contains proper policy suggestions based on the findings. [ABSTRACT FROM AUTHOR]

Attributed to the growing focus on energy savings and eco-friendliness, the solar PV-based DC Nano-grids for residential and commercial buildings are becoming more popular. On the other hand, solar photovoltaic systems (SPV) are intermittent and unreliable due to their dependency on external factors such as solar irradiance, ambient temperature, and unpredictable shadows. In addition, the power degradation occurs in SPV systems due to module mismatch losses caused by various factors like partial shading (PS), dissimilar aging effect, different power ratings, etc. The conventional PV system cannot handle all these issues, so it is essential to address them. This paper proposes a bidirectional modular PV battery system (BMPBS) that uses non-isolated buck and boost converter combinations. This system is capable of self-sustained generation, storage, and bidirectional power flow within the Nano-grid. The proposed BMPBS can handle losses due to module mismatch and intermittency in SPV with the help of battery storage system (BSS), making the overall SPV system reliable. It requires single-stage power conversion to extract maximum power from each PV module and BSS charging and discharging. Its modular design allows it to function across various voltage, power, and BSS choices. This paper discusses the operation, steady-state analysis, and dynamic analysis of the proposed BMPBS. The performance of the proposed BMPBS is validated using a state-of-the-art experimental setup with two PV modules, each having a rating of 90 W P . • The proposed BMPBS is capable of self-sustained generation, storage, and bidirectional power flow within the Nano-grid. • The proposed BMPBS can handle open circuit in SPV or battery module. • The proposed BMPBS can mitigate the module mismatch losses of solar PV (SPV). • The proposed BMPBS is able to handle intermittency in SPV with the help of a battery storage system (BSS). • This system requires single stage power conversion increasing the overall efficiency. • This system uses single inductor making the overall system compact. • Its modular design allows it to function across various voltage, power, and BSS choices. [ABSTRACT FROM AUTHOR]

Vanadium Flow Batteries (VFBs) are a stationary energy storage technology, that can play a pivotal role in the integration of renewable sources into the electrical grid, thanks to unique advantages like power and energy independent sizing, no risk of explosion or fire and extremely long operating life. The first part of this paper presents the main features and the basic performance parameters of VFB, which determine their electric, hydraulic, thermal, and aging feature. The latter part outlines the strengths and weaknesses of the technology, the services that it can provide to the grid, and a short economic analysis. After presenting the fundaments of the technology, prospects and trends of VFBs deployment are outlined. Most of the considerations highlighted in this paper are inspired to studies performed on an industrial-size VFB operated at the Electrochemical Energy Storage and Conversion Lab (EESCoLab) at the University of Padua (Italy). [ABSTRACT FROM AUTHOR]

Along with the popularity of the environment, social and governance (ESG) concerns, the circular economy concept has gained tremendous attraction from the industries, policy makers and academicians. On a firm level, this is implemented through the so-called Circular Business Model (CBM), which is seen through various initiatives. This includes firms in the energy industry, who are transitioning from conventional to renewable energy sources. Nevertheless, despite of the importance and the omnipresence of the practice, there is still lack of empirical research within the CBM topic. In particular, empirical research combining the CBM and technological innovation topic within energy industry (as technology-intensive and high risk industry) in developing country such as Indonesia, is still lacking. To answer this gap, using literature review as research method, this paper has arrived into the following propositions as main result; (1) there is a positive relationship between firm's level of CBM and technology innovation adoption to firm's performance, where (2) the two antecedents that are positively impacting firm's level of CBM and technology innovation adoption are leader's innovativeness and perceived level of technology. For academicians, this research is expected to provide contribution to the energy transition literatures within CBM and technology innovation adoption topic. Propositions provided in this paper is expected to serve as valuable basis in conducting further empirical research. For practitioners, this research is expected to provide valuable insights to make improvements and/or innovations in terms of business model, technology adoption, and strategy. At last, this research is expected to support energy transition. [ABSTRACT FROM AUTHOR]

This paper examines the impact of green finance on environmental performance in developing countries. Using panel cointegration analysis and panel vector error correction model (VECM) to a sample of 76 developing economies from 2010 to 2019, this study confirms that carbon emissions (CO 2) is cointegrated with green finance, real gross domestic product, urbanization, and renewable energy under different specifications and therefore we estimate the long-run relationships among these variables. Specifically, both green finance and renewable energy are found to exert significant and inhibitory effects on CO 2 emissions, reaffirming the necessity to promote green finance and renewable energy. Results from the paper also document the existence of the Environmental Kuznets Curve and the increasing effects of urbanization on CO 2 emissions. Several policy implications and recommendations are drawn from this study. • We examine impact of green finance on environmental performance. • 76 developing economies from 2010 to 2019 are considered. • Green finance and renewable energy exert inhibitory effects on CO 2 emissions. • Results support the existence of the Environmental Kuznets Curve. [ABSTRACT FROM AUTHOR]

Effective 3D anode was prepared by graphitization of corncob biomass at high temperature under an inert atmosphere. As an anode in the microbial fuel cells, the proposed electrode revealed very good performance in both batch and continuous modes when the process parameters were optimized. The physicochemical characterizations indicated that the surface of the prepared anode is decorated by micro porous layers array and composed of SiO 2 ‒incorporated graphite. Moreover, investigation the electrical properties showed very good electrical conductivity dependent on the preparation temperature; 6.9, 8.6 and 8.9 S/m for the electrode prepared at 900, 1000 and 1100 °C, respectively. The performance of the proposed anode was evaluated in air‒cathode single chamber microbial fuel cell driven by domestic wastewater without using exterior microorganisms. The electrochemical measurements, for the batch mode cell, displayed high power density generation upon utilizing the corncob electrode compared to commercial anodes; 100 ± 8, 135 ± 11 and 2010 ± 85 mW/m2 from cells assembled using carbon paper, carbon cloth and corncob‒1100 °C, respectively. Moreover, addition of sodium acetate strongly enhanced the cell performance as the generated power density was increased from 475 ± 30 to 1963 ± 90 mW/m2 after addition of the salt (5 g/l), however the experimental results indicated that 5 g/l is the optimum salt concentration. In a continuous mode cell, the results concluded that the proposed 3D anode can be used fresh or after colonization of a biofilm. Interestingly, the generated power from the continuous mode cell is higher than the batch mode system due to mass transfer resistance elimination. • Corncob has been successfully exploited as an effective anode in the microbial fuel cells. • The introduced anode has been utilized in batch and continuous mode cells. • The generated power density reached to be twenty folds compared to commercial electrodes. • The detected power density was further improved in continuous mode microbial fuel cells. [ABSTRACT FROM AUTHOR]

Urban energy supply includes more renewable energy, but renewable energy, such as wind and photovoltaic, is intermittent and connected to the grid and impacts the safe operation of the power system. For urban multi-type energy dispatching, this paper proposed a day-ahead multi-energy robust optimization dispatching method for an urban power grid with a high proportion of renewable power. Firstly, the power supply and load operation scenarios of the urban energy supply system are constructed. Multiple typical scenarios are formed based on fully considering the uncertainties caused by renewable energy and load prediction. A robust optimal scheduling model with system constraints was constructed based on the tuning capacity of adjustable generator sets and energy storage devices in the power grid, with multi-system functional cost optimization as the objective function. Extending the augmented Lagrange multiplier Method, the Alternating Direction Method of Multipliers (ADMM) is proposed to solve the constructed model. The effectiveness of the proposed method is verified by some examples based on the data of an actual power grid in China. [ABSTRACT FROM AUTHOR]

Green steel, produced using renewable energy and hydrogen, presents a promising avenue to decarbonize steel manufacturing and expand the hydrogen industry. Australia, endowed with abundant renewable resources and iron ore deposits, is ideally placed to support this global effort. This paper's two-step analytical approach offers the first comprehensive assessment of Australia's potential to develop green steel as a value-added export commodity. The Economic Fairways modelling reveals a strong alignment between prospective hydrogen hubs and current and future iron ore operations, enabling shared infrastructure development and first-mover advantages. By employing a site-based system optimization that integrates both wind and solar power sources, the cost of producing green steel could decrease significantly to around AU$900 per tonne by 2030 and AU$750 per tonne by 2050. Moreover, replacing 1% of global steel production would require 35 GW of well-optimized wind and solar photovoltaics, 11 GW of hydrogen electrolysers, and 1000 square kilometres of land. Sensitivity analysis further indicates that iron ore prices would exert a long-term influence on green steel prices. Overall, this study highlights the opportunities and challenges facing the Australian iron ore industry in contributing to the decarbonization of the global steel sector, underscoring the crucial role of government support in driving the growth and development of the green steel industry. [Display omitted] • Australia could produce low-cost green steel for value-added export • Strong correlation between hydrogen hubs and iron ore operations • Existing infrastructure supports the roll-out of the industry • Optimized generation mix reduces storage, curtailment and production costs • Iron ore prices substantially influence green steel prices in the long term [ABSTRACT FROM AUTHOR]

The primary purpose of this paper is to investigate the effects of two variables, trade openness and the issuance of green bonds, on the consumption of renewable energy in Southeast Asian countries. Quarterly data throughout 2016–2021 in the framework of the panel data method were used for the case of 6 selected countries (Indonesia, Malaysia, Philippines, Singapore, Thailand, and Vietnam). The results confirmed that the issuance of green bonds is an effective green financing tool in the implementation of the development policy of the deployment of renewable energy in the countries of the Southeast Asian region. The degree of trade openness has a driving effect on increasing renewable energy consumption due to the increased possibility of transferring green technologies and increasing interactions with leading countries in the field of sustainable development. The typical standard of green bonds, green scientific network (GSN), the development of e-commerce, and the publication of digital green papers are the recommended practical policies of this research. • Green bond is an effective tool to increase of deployment of renewable energy. • Trade liberalism increases the deployment of renewable energy. • Green R&D is a leading factor in the field of clean energy consumption. [ABSTRACT FROM AUTHOR]

Sustainable energy demand drives innovation in energy production. Electrolysis of water can produce carbon-free hydrogen from renewable sources. This paper presents a bibliometric analysis of recent and highly referenced research on hydrogen electrolysers utilising the Scopus database to shed insight into future trends and applications. It has been discovered that the most frequently published type of study for top-ranked papers is the formulation of problems and simulations (38.3%), followed by a study of the state-of-the-art technology assessment (32.5%), laboratory research, design, and performance evaluation (24.2%), and reviews (5%). In general, 33.33% of articles focused on controlling hydrogen electrolyser efficiency. This study used different case studies from the global literature to conduct a complete evaluation of the electrolyser statistical analysis of the present state of the art, models or modes of operation, key challenges, outstanding issues, and future research. This evaluation will aid researchers in building a commercially successful hydrogen electrolyser. • A comprehensive review on hydrogen electrolyser is analysed for future research directions. • The problems, state-of-the-art technology, design, and performance evaluation is reviewed. • The control strategies are significantly boost the efficiency of hydrogen electrolysers. • A statistical analysis on electrolyser models, open issues, and future research trend is investigated. • This review will contribute to improve the efficiency and sustainability of electrolyser technology. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage system (HESS) has excellent potential in high-proportion renewable energy systems due to its high energy density and seasonal storage characteristics. After detailing the volatility of wind speed, irradiance and load, this paper proposes a bi-level optimization model to analyze the economic operation of the wind-photovoltaic-hydrogen hybrid system (WPH-HS). First, the relationship between the source-load output matching and operating conditions of HESS is studied, two evaluation indicators are described, which can be adjusted by wind-solar complementarity on the source side and demand response on the load side. Second, considering the levelized cost of storage (LCOS), the total annual cost (TAC) calculation method of WPH-HS is presented, and this paper provides a new hybrid optimization technology of chaotic search, particle swarm optimization and non-dominated sorting genetic algorithm2. Finally, the system is simulated with the MATLAB software to determine the optimal sizing of components and minimize the LCOS while ensuring the optimal TAC. The simulation results are elaborated in detail. In particular, the added source-load interaction reduces the TAC and LCOS by 7.3% and 10.3%. When two indicators reach 0.03 and 0.1745, the system is economically viable with the LCOS of 0.276 USD/kWh. The hybrid optimization algorithm can achieve better result in fewer iterations. • The cross-season utilization of the hydrogen energy storage system is discussed. • A price bi-level model about the levelized cost of storage and the total annual cost is established. • Evaluation indicators are presented to promote the source-load interaction. • Effects of wind speed, irradiance, and loads are investigated for the levelized cost of storage. • A hybrid optimization algorithm based on three common algorithms is designed. [ABSTRACT FROM AUTHOR]

Power-to-ammonia (P2A) technology has attracted more and more attention since ammonia is recognized as a natural zero-carbon fuel. In this context, this paper constructs a renewable energy powered multi-energy hub (MEH) system which integrates with a thermo-electrochemical effect based P2A facility. Subsequently, the energy management of proposed MEH system is casted to a multi-agent coordinated optimization problem, which aims to minimize operating cost and carbon dioxide emissions while satisfying constraints. Then, a novel multi-agent deep reinforcement learning method called CommNet is applied to solve this problem to obtain the optimal coordinated energy management strategy of each energy hub by achieving the distributed computation of global information. Finally, the simulation results show that the proposed method can achieve better performance on reducing operating cost and carbon emissions than other benchmark methods. [ABSTRACT FROM AUTHOR]

• We employed MRA to specify the authentic empirical effect based on 328 estimation results from 33 primary studies. • Financial development leads to higher renewable energy consumption / use / capacity / production according to the MRA. • There is no publication bias in the existing literature. • The authentic empirical effect may change depending on financial development or renewable energy indicators used, time period covered, the unit analyzed, and the estimation technique employed. • There is an omitted variable bias in the existing literature. The current paper tries to determine and quantify the authentic empirical effect of financial development on renewable energy beyond publication selection bias, if any, based on 328 estimation results from 33 primary studies that were published or presented over the period of 2009-2022. Bivariate and multivariate FAT-PET analyses were used as tools of meta-regression analysis. A positive significant authentic empirical effect of financial development on renewable energy is found as a first contribution. Hence the results support Hypothesis 1; by offering more reliable, efficient, and less costly funds to investors; whether private or public, financial development boosts renewable energy. An absence of publication bias is resulted regarding the overall findings of the primary studies or design characteristics (moderating variables) as a second contribution. Based on the results for moderating variables, the authentic empirical effect may change in direction and magnitude due to the financial development or renewable energy indicators used, the time period covered, the unit analyzed, and/or the estimation technique employed as a third contribution. Omitted variable bias is found in the existing literature analyzing this subject. [ABSTRACT FROM AUTHOR]

The tragedy of the depletion of natural resources led by their overconsumption has posed severe deleterious effects on humanity and the environment. Post-consumption-led waste has worsened the situation, given that unregulated and unscientific waste treatment furthers the criticality of ecological dilapidation. To curb ecological overshoot and restore the full capacity of ecosystem services, we need to focus more on recycling the available resources at their maximum capacity. In other words, we must take a U-turn from the linear economic system to the circular one. The issue is that the number of real-world data-driven scientific studies is very scant in this sphere of literature. Against this milieu, this paper scrutinizes the effect of a circular economy on CO2 emissions intensity among a panel of the top seven CO2 emitters of the world. We have used data from 1990 to 2020 and applied the Augmented Mean Group (AMG) technique to reach our empirical conclusions. By controlling for globalization and renewable energy consumption, we unveil that municipal waste, a crucial component of the circular economy, is positively entangled with CO2 emissions among the designated nations. This observation further reiterates the theoretical underpinning and urges to harness municipal waste as a valuable raw material for a circular economy. Moreover, we disclose that economic growth and globalization boost CO2 emissions intensity among the designated nations. Contrarily, the consumption of renewables helps uplift environmental integrity. Our conclusions also hold after the robustness check. Further, the D-H causality test establishes a bidirectional causality between municipal waste and CO2 emissions. One-lane causality is also observed from a linear economy to a circular economy. More specifically, municipal waste is observed as a critical determinant of pollution and carbon emissions. In light of the findings, the authors provide novel policy recommendations apropos sustainable development goals. [ABSTRACT FROM AUTHOR]

World electricity consumption has grown permanently since 1990, dramatically increasing the emission of greenhouse gases. The worldwide efforts to reduce them and address climate change are leading to the massive electrification of different end-users, increasing the power demand. Therefore, achieving Sustainable Development Goals regarding affordable and clean energy requires the extensive availability of capital investments in electricity generation from renewable sources. Project Finance (PF) is a suitable financing alternative for large projects. This paper presents the advantages of PF contracts in allocating risks to appropriate counterparts and reducing the likelihood of default. Additionally, this study analyzes the characteristics that favor PF financing for renewable energy projects. The results reveal that country's governance levels, well-developed financial systems, and project costs affect the financing probability of a PF initiative, particularly for low and middle-income countries. Therefore, public policies aimed at increasing the availability of resources to renewable projects must tackle these factors. • The world requires massive renewable energy investments to meet Sustainable Goals. • Project Finance is a widely financing structure for large investment projects. • We study the determinants of renewable energy Project Finance. • Low governance and financial development hinder renewable energy PF initiatives. • Policies to develop capital markets and PF will help to reach the net zero target. [ABSTRACT FROM AUTHOR]

This study aims to investigate the gasification potential of olive pomace with using different fixed-bed gasifier systems. Olive pomace as a dried form was supplied from a chemical industry plant working on olive oil soap, located in Izmir, Türkiye. After a complete characterization of olive pomace, gasification experiments by using fixed bed reactor systems were done at three different gasifier temperatures as 700, 800 and 900 °C. As a gasification agent, dry air was used with four different flowrates (0.4, 0.2, 0.1, 0.05 L/min) while pure oxygen experiments were carried out with a flow rate of 0.01 L/min. Syngas with H 2 content of 48% and 45% (volumetric) were obtained in updraft and downdraft gasifiers, respectively, by using dried air as a gasifying agent. Heating value of syngas was around 12.4 MJ/Nm3. In the pure oxygen atmosphere, H 2 contents of the syngas were measured as 53% and 39%vol. In the updraft and downdraft gasifiers. This paper presents the research results on the olive pomace gasification study as a part of a large-scale research project and discuss them in the context of hydrogen production from the fixed bed reactors. [Display omitted] • Pomace gasification process was carried out in two different fixed bed reactors. • The volumetric percentage of H 2 gas was found to be in the range of 40–50%. • The maximum volume of methane was measured approximately as 20%. • The maximum volume of CO was measured in the range of 20–30% in both reactors. • The maximum volume of hydrogen in the updraft gasifier was measured as 48%. [ABSTRACT FROM AUTHOR]

The fundamental way for China to achieve carbon peak and carbon neutrality is to continuously improve the penetration of renewable energy (RE) in the power system and establish an electricity mix dominated by RE power. According to China's 14th Five-Year Plan, the proportion of non-fossil energy power generation should reach about 39% by 2025. However, the impact of the increase in share of RE power on carbon emissions of the electricity sector remains to be estimated. To this end, the purpose of this paper is to capture the nonlinear characteristics of RE on electricity-related carbon emissions by using panel smooth transition regression (PSTR) model and provincial panel data covering the period 1991–2020 under the background of provincial RE quota system. The estimation results indicate that, (i) in the four transition variables of PSTR model such as the installed capacity of power generation, substation equipment capacity, total electricity consumption and total power generation, the nexus between RE deployment and electricity-related carbon emissions was detected as nonlinear. (ii) The heterogeneous RE carbon abatement effect is reflected in its increasing penetration in provincial power systems. (iii) Carbon abatement performance of RE generation decreases in the negative range with the increase of transition variables. (iv) The estimation coefficient of RE is positive at the higher value of the transition variable in the PSTR model of carbon emissions per capita. As a result, the RE quota with the best emission abatement performance should be designed based on the provincial power resource endowment and the medium and long-term expected electricity consumption. [ABSTRACT FROM AUTHOR]

In recent decades, the role of green energy in realizing green transition and addressing environmental degradation needs to be brought into full play. To promote green energy development in China, this paper examines the relationship among green economic growth, green finance, and green energy (3G) between 2011 and 2019. The heterogeneous, asymmetric, and mediation impact relationship that exists in the 3G nexus is also explored in this study. Accordingly, the results suggest that: (1) Green economic growth and green finance are positively associated with green energy, and the impact is heterogeneous on different types of green energy and in different regions; (2) the impact of green economic growth on green energy are asymmetric, while that of green finance is consistent; and (3) green innovative technology is an effective mediator between green economic growth and green energy, while the investment effect is not significant. This paper contributes to formulating several reasonable policies for improving the green energy industry and achieving sustainable development. It is essential to give full play to the transformation of green achievements to enhance the role of green economic growth in promoting the green energy industry. • This study explores 3G nexus (green economic growth, finance, and energy (GRE)) in China. • The heterogeneity, asymmetry, and mediating mechanism are further analyzed. • Green economic growth and green finance can significantly promote GRE. • The impacts of green economic growth and green finance on GRE are heterogeneous. • Green technological innovation is an effective mediator in the 3G nexus. [ABSTRACT FROM AUTHOR]

Given global warming, which limits the use of classical energy sources, renewables can provide a solution to the dilemma between environmental protection and sustainable economic growth. In this complex and changing context, green hydrogen can become a promising link between renewable energy sources and end users. However, although hydrogen has a high gravitational energy density, it has a very low volumetric energy density. This challenge requires hydrogen compression at several stages in the supply chain from electrolysis units to conversion, storage, and distribution. Recently, many studies have focused on hydrogen compression technologies. This paper provides an overview of recent advances in large-scale hydrogen compression. First, the role of hydrogen compression in providing clean energy for the future is explored. Then the thermodynamic concept of hydrogen compression is investigated. Gaining a proper understanding of compressor operating conditions in various operations in the large hydrogen industry is the next focus of this paper. Later, the capabilities and limitations of available mechanical compressors for the hydrogen industry, including reciprocation and centrifugal, are summarized. Finally, research gap and recommended new areas in this field are recognized. The presented insightful concepts provide students, experts, researchers, and decision-making working on large-scale hydrogen industry with the state of the art in hydrogen compressors industry. • Green hydrogen is a promising link between production and use of renewables. • Low molecular weight of hydrogen makes compression a crucial step in the green hydrogen chain. • Various operations in this industry need compressors with output pressures of 20 bar–200 bar. • Only reciprocating and centrifugal compressors can handle the required capacity in this industry. • Review of resources proves rapid progress in the design and reliability of hydrogen compressors. [ABSTRACT FROM AUTHOR]

Despite their economic success, the BRICS countries have yet to achieve environmental sustainability. On the other hand, these countries will not be able to maintain their economic expansion if they do not protect the natural environment. In this regard, this paper intends to assess the effects of financial integration (globalization) on ecological footprint. The paper also considers other ecological footprint drivers, including economic expansion, urbanization, renewable energy and technological innovation. The research utilizes a dataset spanning from 1990 to 2018. The study employed the method of moments quantile regression (MMQR) approach, which is robust to cross-sectional dependence and slope homogeneity issues. The outcomes from the MMQR disclose that the effect of financial globalization on ecological footprint is positive across all quantiles (0.1–0.90), thus validating the pollution haven hypothesis (PHH) in the BRICS nations. Furthermore, both renewable energy and technological innovation curb ecological footprint across all quantiles (0.1–0.90). Moreover, technological innovation is proven to impact the environment positively across all quantiles (0.1–0.90) via the path of urbanization. As a result, technological innovation is projected to help the BRICS nations achieve sustainable urbanization. The DOLS, FMOLS, FE-OLS outcomes also validate the outcomes of MMQR. Based on these results, policies were proposed. • MMQR applied to integrate asymmetric effects. • Renewable energy consumption and technological innovation derive ecological sustainability. • Financial integration-led Pollution-haven-hypothesis is confirmed. • Economic growth and urbanization lead to higher ecological footprints. • Technology innovation neutralizes the negative impact of urbanization on ecological sustainability. [ABSTRACT FROM AUTHOR]

This paper uses panel data on renewable energy in China. Thus, the current analysis fills the gaps by examining the relationship between green technology innovation and renewable energy and CO 2 emissions from 1990 to 2018. The current study examines all concerns connected to panel data analysis with advanced panel estimators, such as cross-sectional dependence, stationarity, variation in slope parameters, and structural break. Our findings show that test results reveal that green technology innovation and renewable energy have a negative and considerable influence on CO2 emissions in the long run. Moreover, the short-run relationship of green technology innovation, on the other hand, is not significant—as evidenced by the findings of robustness tests such as AMG and CCEMG. Other empirical results revealed that GTI, REN and NEN significantly reduced local CO 2 emission, while POP and PI had no obvious reduction effects on CO 2 emissions. Different GTIs had the same spatial "symbiotic effects" on CO 2 emission reduction in the short term, showing positive spatial spillover reduction effects. Lastly, we conclude that the use of green technology innovation has positive externalities. Some policies to assist green innovation technologies and renewable energy resources have been suggested for the Chinese government to enact. • This paper uses panel data on renewable energy in China. • The current study examines all concerns connected to panel data analysis with advanced panel estimators. • The short-run relationship of green technology innovation is not significant. • We conclude that the use of green technology innovation has positive externalities. [ABSTRACT FROM AUTHOR]

• Impacts of export quality on economic progress are examined. • The role of economic complexity for economic growth is investigated. • 28 OECD country's data is utilized from 1990 to 2019. • Export quality and economic complexity induce sustainable growth. • Institutional quality is a significant determinant for economic growth. It is important to unearth the role of structural change factors for sustainable growth in developed economies. Economic complexity, export product quality, and institutional indicators represent the overall structural change and transformation in an economy. This paper probed the influence of export product quality and economics of complexity on economic growth for 28 OECD (Organization for Economic Co-operation and Development) countries using the data from 1990 to 2019. In doing so, the study employs three-panel data econometric models to investigate the role of economic complexity, export quality, and institutional quality on economic development. The paper performs the empirical tests, including the cross-sectional related dependency methods and cointegration techniques. As per the results emerging from fully modified OLS (FMOLS) and dynamic OLS (DOLS) estimation, export quality and financial development positively and significantly strongly impact growth in the long run. The empirical conclusions report detailed discussion on sustainable growth and discuss novel implications concerning product quality and institutional performance. The conclusions stress the practical implications for sustainable economic growth of OECD economies. [ABSTRACT FROM AUTHOR]

With global climate change posing a major threat to human society, a growing number of countries have taken "carbon-neutral" as a national strategy and proposed a vision of carbon-free future. As an important supplement to traditional fossil energy, renewable energy is the main force to reduce the use of high-carbon energy and carbon dioxide emissions, which will become the trend of social development in the future. Finding the optimal renewable energy source is of particular significance for achieving the net zero emissions. However, the existing evaluation methods of renewable energy sources have obvious shortcomings. In terms of weight calculation methods, such as the randomness of the subjective method is strong and the index weights do not reflect the small changes of the evaluation matrix, which affect the reliability and accuracy of the evaluation result. The existing ranking methods can only achieve the complete ranking of the different objects, but cannot classify the renewable energy technical alternatives into different grades. Given this background, this paper proposes a novel evaluation method for renewable energy plans based on improved sparrow search algorithm and projection pursuit model. Firstly, this paper improves the traditional sparrow search algorithm from three aspects: population initialization, population update and population variation. Then, the projection pursuit model is constructed, and the improved sparrow search algorithm is applied to optimize the projection target to find the optimal projection direction, so as to determine the weight values of each evaluation index. Finally, the weighted rank-sum ratio method is used to select the best renewable energy technical plan, which can not only realize the complete ranking of different plans, but also classify the technical plans into different levels. Based on the actual renewable energy development data from a province in China, experiments were carried out to investigate the effectiveness of the proposed method. Experimental results show that the proposed method performs better than some existing evaluation methods of renewable energy technical plans. [ABSTRACT FROM AUTHOR]

A successful and just energy transition is subject to policies that adhere to a multi-dimensional approach to renewable energy development. To achieve success in renewable energy development, well-thought-out and efficient policies must be implemented. This paper aims to address a major shortcoming in renewable energy development in terms of understanding and recognising the policy space that promotes or hampers renewable energy growth. The paper examines the relevant literature to identify major themes and factors in renewable energy development. A thematic analysis was conducted using a hybrid inductive and deductive approach and resulted in the identification of 5 major themes namely Institutional, Environmental, Financial, Socio-cultural, Technical and 144 factors. The identified themes and factors will assist to make a policy action decisive, just, and sustainable. Recommendations including comprehensive incentivisation, regulatory support for renewable energy technologies in developing nations, environment impact assessment programs, promotion of financial transparency and opting for a just transition to benefit local and vulnerable communities. [ABSTRACT FROM AUTHOR]

Carbon emission flow is an effective tool to obtain carbon emission distribution in power systems, which can guide the active carbon reductions of consumers through proper incentive schemes. With the increasing penetration of renewable energy, the existing single-valued carbon emission flow model based on deterministic forecasted power outputs cannot describe the impacts of renewable energy uncertainties on carbon flows. Therefore, this paper mainly focuses on the assessment of the probabilistic carbon emission flow through the power systems considering the impacts of load and renewable energy uncertainties. In this paper, the probabilistic carbon emission flow (PCEF) is innovatively proposed. With the PCEF, consumers can make better energy use plans considering their own risk appetites for carbon emission payment. Firstly, the impact factors of the PCEF are modeled, including load and renewable energy uncertainties and integrated carbon intensity of thermal plants. The uncertainties of load, wind power and photovoltaics are modeled based on a p-box method while the uncertainty of hydropower is modeled based on the multi-state model. Besides, the integrated carbon intensity model of thermal plants are proposed considering the carbon intensity variations during the operating, start-up, and shut-down stages. Furthermore, the probabilistic carbon emission evaluation framework is proposed to assess the probabilistic carbon distribution. In this framework, novel probabilistic carbon indices are defined to precisely characterize the carbon emission situation with probabilistic representations. A solution method based on an adaptive interval point estimation (AIPEM) algorithm is proposed to efficiently solve the developed evaluation problem. Tests on an IEEE-30 node system, and a real provincial power system in China validate the effectiveness and application of the proposed model. The results showed that the PCEF can be a useful tool for obtaining the probabilistic representation of carbon emission flow and guiding the consumers' active carbon reduction in power systems. • Probabilistic carbon emission flow is proposed considering multiple uncertainties. • Integrated carbon intensity model for thermal plants is developed. • A p-box model is used to describe the uncertainties of load and renewable energy. • PCEF can help consumers balance the cost and carbon risk when making decisions. [ABSTRACT FROM AUTHOR]

Given the increasing penetration of Inverter-Based Resources (IBR) and the impacts of these generators on existing fault location functions, this paper explores the potential of Machine Learning (ML) for designing one-terminal fault locators applied to systems with IBRs. For the studies, a system with a widely used topology for IBR interconnection to a transmission grid is modeled in PSCAD software, considering fault scenarios on the interconnection line with varying fault parameters, in addition to different IBR controls/topologies, grid short-circuit levels and signal noise levels. Besides the investigations on correctly choosing the attributes extracted from the signals for training ML methods, which introduces the concept of learning based on the existing method's response, the studies cover performance assessments of 35 ML methods for the fault location task, indicating the most suitable ones, and studies about the influence of the training set size on the ML methods performance. Moreover, comparative performance analyses are conducted between the ML-based methodology and state-of-the-art fault locators, highlighting the benefits of the ML-based approach in reducing errors obtained in the fault location task. Finally, the paper recommends stages for applying ML-based methods to real systems, besides providing insights and recommendations on such practical applications. • IBR significantly impacts traditional one-terminal phasor-based fault locators. • Machine learning methods can be adopted to minimize errors in the fault location task. • A new learning concept based on the response of existing methods is presented. • The practical implementation bias of machine learning methods is explored. [ABSTRACT FROM AUTHOR]

• Pioneer Spain: first country to include in grid code the synthetic inertia capability. • Synthetic inertial response of a PV inverter studied based on the Spanish grid code. • Analyzed the role of power plant controller in the dynamic response of the facility. • PV system able to contribute to frequency control providing an inertial response. As the large-scale integration of renewable energy grows, inertia in power systems is reduced, which causes the rate of change of frequency to increase and worsens the frequency nadir during disturbances. There is, therefore, an urgent need to accelerate the development of international standards and regulations that require solar PV systems and other renewable installations to also contribute to stability in the network by emulating inertia. Spain is a pioneer in this field: it is currently the only country that includes the synthetic inertia technical requirement in its grid code. In this context, the present paper analyzes the synthetic inertial response of a PV system model that forms part of an actual PV power plant in Spain under two scenarios, according to its grid code: i) when measurements are conducted at the power conversion PV system level and hence only its control algorithms are executed; and ii) when measurements are conducted at the power plant level and the power plant controller also influences the response of the entire installation. Among its aims, this paper seeks to thoroughly assess the response of an actual PV power conversion system that has the capability of actively contributing to frequency regulation in a network and to critically analyze the suitability of having a power plant controller when the PV facility contributes to power-frequency control by means of an inertial response. The results reveal, at the power conversion PV system level, that the inertia emulation module significantly reduces the response times of the installation to changes in frequency -by more than 68% in the worst case under frequency increases, and by 73% under frequency decreases, thus contributing to more rapid power-frequency regulation in the network. However, at the power plant level, the power plant controller disturbs the PV power conversion system's behavior and causes the opposite effect: response times increase -up to more than 7% in the most unfavorable case when the inertia module is enabled. [ABSTRACT FROM AUTHOR]

In the last years, the massive deployment of new photovoltaic (PV) power plants has launched the connection of PV inverters to the electrical network. A single medium-sized ground-mounted PV plant may have thousands of these inverters linked to the grid and even more PV panels on the DC side. Upon reaching such a substantial magnitude of devices involved in grid-connected installations, the effective operation, management, predictive maintenance, and fault detection becomes increasingly challenging without integrating advanced prediction and automated anomaly detection systems. Artificial intelligence algorithms, grounded in data measurements, can be pivotal in addressing this challenge. This paper proposes several regression-based methods to predict PV plants' energy generation, which is useful for detecting transient and long-term anomalies. These models are trained using a Recursive Least Squares (RLS) method and require a minimum number of variables to yield satisfactory outcomes, which is one of the paper's contributions. They mainly rely on energy generation measurements and geolocation. Within the scope of this research, two distinct algorithms have been implemented and validated. The first algorithm, a simplified model, is engineered to analyse the daily efficiency variation, prioritizing the identification of faults and abnormal operational profiles in PV plants. On the other hand, the second algorithm adopts a more intricate model tailored to facilitate long-term diagnosis, enabling the assessment of PV efficiency degradation. In this work, both algorithms are described and their performance is validated using the historical data from more than 20 PV plants placed in different climatic regions. • Photovoltaic systems' modelling using linear regression models. • Photovoltaic fault detection using linear regression coefficients evaluation. • Automatic fault detection for photovoltaic plants with low sensors' availability. • Short-term and long-term efficiency trend evaluation of photovoltaic plants. [ABSTRACT FROM AUTHOR]

Green ammonia, a promising zero-carbon energy storage vector, has never been produced using solely tidal stream energy despite its predictable characteristics. Combining tidal stream sites with a phase difference (tidal phasing) facilitates anticorrelation between these sites' power profiles, enabling a more consistent power output. Green ammonia production benefits from a steady and predictable power input. The objective of this paper is to determine if nearby tidal sites have a large enough phase difference (anticorrelation) to reduce the cost of ammonia production. Moreover, producing green ammonia from underutilized or unutilized remote and grid-constrained tidal stream sites may enable viability of these sites. This paper is the first analysis of green ammonia production using solely tidal stream energy and the first analysis of tidal phasing for green fuel production. Two UK case studies are presented in i) the North Channel of the Irish Sea and ii) Orkney. There are tidal sites in each which have a phase difference (e.g. the Mull of Kintyre/Sound of Islay, and Graemsay/North Ronaldsay with correlation coefficients of 0.17 and −0.02 respectively), utilising this phase difference reduces the levelized cost of ammonia by 8% in the Irish Sea and by 12% in Orkney. [ABSTRACT FROM AUTHOR]

In recent decades, the use of fossil fuels has had a harsh impact on the climate, and the frequency and intensity of various extreme weather events have increased, which has triggered an increased the use of renewable energy sources and reflection on technological advances. Many countries are trying to promote renewable energy to reduce their impact on climate change, but the impact of national energy policies in the climate risk framework remains poorly understood. Based on the panel data of 84 developed/developing countries around the world from 2006 to 2019, this paper studies and analyzes the impact of renewable energy use on climate risk. The study found that the increase in the proportion of renewable energy use can reduce the climate risk, and this result is still robust after undergoing robustness tests such as changing variables, samples, and research methods. The findings offer an important solution for European countries, where climate risks are most acute. The heterogeneity analysis shows that the higher the level of economic development, population density and the lower the level of incorruptibility, the weaker the inhibitory effect of renewable energy use on climate risk. The mechanism analysis also shows that the increase in the proportion of renewable energy use can reduce climate risk by reducing carbon dioxide (CO 2), methane (CH 4), nitrogen monoxide (NO), PM2.5 emissions, and the proportion of fossil fuel use, but it does not reduce climate risk by increasing biodiversity. In particular, we find that technological progress has not played a role in the use of renewable energy to reduce climate risk, breaking the stereotype. The policy recommendation of this paper is that under the increasing pressure of climate change, the transition to clean energy is an indispensable option, and the need to accelerate the energy transition becomes more urgent. There is a greater need to further protect biodiversity and enhance technological progress. • The increase in the proportion of renewable energy use can reduce the climate risk. • The mechanism is to reduce CO 2 , CH 4 , NO, PM2.5 emissions and fossil fuels use. • The use of renewable energy cannot reduce climate risks by increasing biodiversity. • The impact of renewable energy use on climate risk is heterogeneous. • Technological progress has not played a role in the use of renewable energy to reduce climate risk. [ABSTRACT FROM AUTHOR]

Decarbonising the heating sector is one of the key elements to realizing the ambitious dual carbon goals of China, which is the largest carbon emitter and energy consumer globally. Currently, district heating (DH) systems have penetrated approximately 88% of the urban heating areas in Northern China. Nevertheless, around 90% of the heating demand in China still relies on fossil fuels. A larger scale integration of renewable energy and waste heat sources into the DH systems is critical for decarbonising the entire heating sector in China. However, a deeper level of comprehension is required to harness its full potential. This paper provides a thorough investigation of the status, potential, and national policy schemes of renewable energy and waste heat recovery in the DH systems of China. Combined with a critical review of recent literature on relevant areas published in both international and Chinese domestic sources, the trends, challenges, and future perspectives are discussed from scientific research and practical implementation aspects. This paper highlights the synergy of the integration of renewable energy and waste heat sources in DH, the energy efficiency improvements as well as the use of thermal storage technologies through the implementation of 4th generation district heating and smart energy systems that could offer a more economically viable pathway forward. • Focus on renewable energy and waste heat (REWH) in the district heating (DH) systems in China. • A systematic review of REWH in Chinese DH systems from status, policy, and literature aspects. • Identification of research gaps based on the review of both international and Chinese journals. • Policy recommendations proposed to promote REWH in Chinese DH systems. • The introduction of international experiences on REWH in DH for analysis in the Chinese context. [ABSTRACT FROM AUTHOR]